Mr. Onur Gilleard
Qualifications & Experience
Mr Onur Gilleard is a distinguished consultant plastic surgeon on the GMC specialist register. He previously held an NHS consultant post at St Bartholomew’s Hospital in London, specialising in skin cancer and microsurgical reconstruction. In 2021, Mr Gilleard transitioned from the NHS to dedicate himself fully to private practice, allowing him to focus exclusively on providing personalised, high-quality care to his patients. He is recognised as an expert in laser treatments, having conducted research and developed advanced treatment protocols using cutting-edge laser technology to optimise both clinical outcomes and cosmetic results.
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A skin tag is not a growth that arrives from outside. It is your own skin, overproducing its ordinary building blocks — loose collagen and a small blood vessel — inside a pouch of normal covering skin. Two forces drive that overproduction: mechanical friction, which is why tags appear where skin rubs, and growth signalling from insulin and hormones, which is why they cluster in some people and not others. Genetics and age set the baseline. A possible role for certain HPV types is debated but unresolved — and, importantly, skin tags are neither contagious nor sexually transmitted. This guide explains the mechanism, and clears out the causes people worry about that have nothing to do with it.
| Section | The question it settles |
|---|---|
| What a tag is made of | Why they are soft, why they bleed, why they sometimes turn black |
| Friction | Why the neck and underarms, and not the forearm |
| Insulin and IGF-1 | Why two people with the same collars get different numbers |
| Hormones, genetics, age | Pregnancy, PCOS, and the slim patient who still gets them |
| The HPV question | Whether a virus is involved, and whether they are catching |
| What does not cause them | Hygiene, shaving, deodorant, and the rest |
| So what | What any of this changes in practice |
What a Skin Tag Is Actually Made Of
A skin tag — an acrochordon, in clinical notes — has a simple and consistent structure. Under the microscope it is a fibrovascular core: loosely arranged collagen bundles with one or more small dilated blood vessels running through them, wrapped in a covering of ordinary epidermis, and attached to the skin by a narrow stalk.
Almost everything patients notice about tags follows directly from that structure:
- They are soft and move freely because the core is loose collagen, not dense tissue.
- They bleed surprisingly well if caught or cut — there is a genuine feeding vessel within the core, which is why home removal with scissors bleeds far more dramatically than patients anticipate.
- They can twist and turn black. A narrow stalk carrying a single vessel can rotate; the blood supply is choked off and the tag infarcts. It looks alarming and is almost always benign — see are skin tags dangerous.
- They are not tumours in any meaningful sense. There is no abnormal cell line — just an excess of the skin’s own normal components in one spot.
That last point is the one worth holding on to. A skin tag is a structural phenomenon, not a disease process. Which is exactly why the question “what causes them” turns out to be a question about mechanical and hormonal signals rather than about infection or illness.
Why Friction Produces Them
Skin responds to repeated mechanical stress by growing. That is useful when it produces a callus on a working hand; it is less welcome when the stress is gentle, constant shear in a skin fold and the result is a tag. Repeated rubbing stimulates local proliferation of exactly the components a tag is made of — fibroblasts laying down collagen, and small vessels growing to supply them.
The distribution gives the mechanism away. A classic European study found skin tags in 46% of adults, most commonly in the armpits and on the neck, with prevalence rising steadily with age (Banik & Lubach, Dermatologica, 1987). Those are not random sites.
| Site | The friction involved |
|---|---|
| Neck | Collars, necklaces, and skin folding on itself when the head turns |
| Underarms | Skin on skin with every arm movement; the single most common site |
| Under the bust | Bra bands and skin-on-skin contact, worse in heat |
| Groin and inner thigh | Walking, waistbands, skin folds |
| Eyelids | Thin, mobile skin, constant blinking and rubbing — see eyelid skin tags |
This is also why weight gain increases tag formation through a purely mechanical route, quite separately from its metabolic effects: more skin folds, more contact, more shear.
The Growth-Signal Side: Insulin and IGF-1
Friction alone does not explain why two people with the same build and the same collars end up with wildly different numbers of tags. The difference is usually in growth signalling.
Skin cells — keratinocytes and fibroblasts — carry receptors for insulin and for insulin-like growth factor 1 (IGF-1). When circulating insulin is persistently high, as it is in insulin resistance, those receptors are stimulated more than they should be, and the cells respond the way cells do to a growth signal: they proliferate. Add friction to mark the spot, and you get a tag.
This is the strongest biological association in the whole topic, and it is well documented rather than speculative. Because it has practical consequences — specifically, whether a blood test is worth requesting from a GP — the evidence and the resulting action are set out in a separate guide: skin tags and insulin resistance, and what skin tags can be a warning for.
The short version for a causes article: one or two tags carry no metabolic significance. A crop developing over months, particularly around the neck, is worth raising with a GP.
Hormones, Genetics and Age
- Pregnancy
- A classic trigger, typically in the second and third trimesters, driven by hormonal change alongside weight gain and increased skin folding. Some tags settle after delivery; most stay and need removing if they bother you.
- PCOS and other insulin-linked conditions
- Work through the same growth-signal route described above, which is why tags are a recognised skin finding in polycystic ovary syndrome.
- Genetics
- Sets the baseline tendency. If one of your parents accumulated tags, you are more likely to. This is the part nobody can change, and it explains the slim, metabolically healthy patient who still produces them.
- Age
- Prevalence climbs steadily through adult life. Tags are uncommon in children and increasingly ordinary from middle age onwards.
The HPV Question
This is the part of the topic where the honest answer is “unresolved”, and where the most anxious questions arise.
Several studies have detected human papillomavirus (HPV) DNA within a proportion of skin tags, which raised the possibility that the virus contributes in some cases. Other studies have looked and found little or nothing. The detection rates vary widely between research groups and between body sites, and finding viral DNA in a lesion is not the same as showing the virus caused it — HPV types are extremely common on normal skin.
What can be said with confidence:
- Skin tags are not a sexually transmitted infection. Whatever the eventual answer on HPV DNA, tags do not behave like an STI and are not treated as one.
- They are not contagious. You cannot catch a skin tag from a partner, a towel or a swimming pool, and you cannot spread your own to someone else.
- Friction and growth signalling remain the dominant, established drivers. The HPV question, whichever way it resolves, does not displace them.
Where this genuinely matters is diagnosis rather than cause. A wart is viral, is contagious, and looks different — rough, firm, often with tiny dark points — where a tag is soft and stalked. Genital tags and genital warts are a particularly important pair to tell apart, and that is a clinical examination rather than a self-assessment. Our comparison guide is here: skin tag vs wart.
What Does Not Cause Skin Tags
Most of what people arrive worrying about is not a cause at all. Clearing these out is half the value of understanding the mechanism.
| The worry | The reality |
|---|---|
| Poor hygiene | No connection. Tags form in scrupulously clean skin; the driver is friction, not dirt. |
| Shaving or waxing | Does not cause tags. Shaving over an existing tag can catch and bleed it, which is how the two get associated. |
| Deodorant or antiperspirant | No evidence of any causal role. The underarm is simply the commonest friction site, so the two coincide. |
| Catching them from someone | Not possible. Tags are not infectious in any form. |
| Cutting one off makes more grow | A persistent myth. Removal does not stimulate new tags; the tendency that produced the first one simply continues — see can skin tags grow back. |
| Toxins, diet or “cleansing” | No mechanism and no evidence. Nothing you drink dissolves a fibrovascular core. |
| Sun exposure | Not a driver of tags, though sun protection matters while a removal site heals. |
| They turn into cancer | They do not. The real risk is the reverse: something that was never a tag being assumed to be one. |
Does Knowing the Cause Change Anything?
Three practical consequences, and one honest limit.
- Friction is the lever you can actually pull. Well-fitting collars and straps, breathable fabrics, keeping folds dry. If a necklace sits exactly where your tags keep appearing, that is the mechanism showing itself.
- A sudden crop is worth a conversation, not a panic. Particularly around the neck, and particularly alongside darker, velvety skin in the same area.
- A lesion that does not behave like a tag needs examining, not explaining. Firm, pigmented, growing quickly, or bleeding without being caught — that is a different assessment, and it is why every lesion is examined before removal.
- The limit: understanding the cause does not reverse it. Existing tags do not shrink, drop off or dissolve with friction control, weight loss or diet. Once formed, a tag stays until it is removed.
Removal itself is quick: small tags are taken off by snip excision or hyfrecation in seconds each under local anaesthetic, and 20 to 30 can be treated in a single session. Cryotherapy is also offered and requires no local anaesthetic, with the trade-off that a tag which does not separate completely needs a second visit. Consultation is £100, the first tag £200 and each additional tag £125 — full detail in our cost guide, or book skin tag removal in Harley Street.
Commonly Blamed Factors, and What the Evidence Supports
Four attributions recur in consultation. The first is the assumption that any tag indicates metabolic disease. It does not: genetics and friction account for a large proportion of tags in individuals with entirely normal blood results, and prevalence rises with age irrespective of build. The insulin association is genuine but is one driver among several, not a verdict on everyone with a lesion. The second is transmission from a partner. Skin tags are not transmissible; shared circumstances — clothing, activity, age — explain the coincidence. Where the site is genital, the lesion to exclude is a wart, which is viral, and that requires examination rather than assumption.
The third attribution is that removal itself provokes further tags. No mechanism supports this. The process that produced the original lesion continues in the same region, and the area is subsequently observed far more closely than before. The fourth concerns diet. Dietary change directed at insulin sensitivity, undertaken with GP support, is worthwhile on its own merits and may reduce the rate of new tag formation. Regimens marketed as “detoxification” aimed at the lesions themselves have no plausible mechanism, and existing tags will not regress.
Frequently Asked Questions
- What actually causes skin tags?
- The skin overproducing its own components — loose collagen and small blood vessels — in one spot, wrapped in normal skin and attached by a stalk. Two forces drive it: repeated friction, which is why tags appear in folds, and growth signalling from insulin and hormones, which is why some people produce many and others none. Genetics and age set the baseline.
- Why do they appear in the armpits and on the neck?
- Because those are the sites of constant, low-grade friction — skin on skin with every arm movement, collars and necklaces on the neck. Skin responds to repeated mechanical stress by growing, and a tag is one version of that response. In the largest classic survey, tags were found in 46% of adults, most often at exactly these two sites.
- Are skin tags caused by a virus like warts are?
- The evidence is mixed. HPV DNA has been detected in a proportion of skin tags in some studies and not in others, and detecting viral DNA is not the same as proving it caused the lesion. What is clear is that skin tags are not contagious and are not a sexually transmitted infection. Warts, by contrast, genuinely are viral and look different.
- Can you catch skin tags from another person?
- No. Skin tags do not spread between people or from one part of your body to another. If several appear in the same area, that is the local friction and your own growth signalling, not transmission.
- Do skin tags mean poor hygiene?
- Not at all, and this is one of the most common anxieties about them. Tags form in meticulously clean skin. The driver is mechanical friction in skin folds, which is a matter of anatomy and clothing rather than washing.
- Can shaving or deodorant cause skin tags?
- Neither causes them. The underarm is simply the single most common site for tags, so anything you do there tends to get blamed. Shaving over an existing tag can catch and bleed it, which is often how people first notice one.
- Does removing a skin tag make more grow?
- No. Removal does not stimulate new tags. A tag taken off at its base is gone permanently, but the tendency that produced it carries on, so new ones can appear elsewhere over time. That is biology, not a reaction to the treatment.
- Can I stop getting skin tags altogether?
- You can reduce the rate rather than switch it off — mainly by cutting friction, and by addressing insulin sensitivity with your GP if that is relevant to you. What none of it does is remove the tags you already have; once formed, a tag stays until it is taken off.
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